api 6a valve material

[DANIAL AZIMI]

As mentioned the requirment of materials for equipment in standard and non standard material table(table no 5) body and bonnet can be 36 up to 75K for example in 5000 class but also indicated that integral end connection flanged shall be only 60,75K,
So if we want to select valve with flanged end and manufacture by forging or casting integrally, we have to use 60K for body and bonnet too, or flanges are from the body parts and can use 36K for 5000 and blow classes??

 

[GD2]

Danial,
When you specify a valve with integrated flanges, the body, bonnet and flanges will be forged/cast from the same material. So you follow one material strength but when you produce the flange to be a weld neck type, API 6A allows you to use two different strength materials.
In general, in piping industry, the flange strengths are usually kept higher due to higher bending stress involved.

Ganga D. Deka, P. Eng
Canada

 

[DANIAL AZIMI]

Thanks but my quastion is about the first part of your answer, i means that when we produce flanged valve by forge or cast as you mentioned also , we shall made it in the same material , which material is accepted, body and bonnet requirment as 36k,45k and 60k for whole parts( body and flange) or only 60k is accepted?
In my opinion, the whole parts of flanged valve are known as body and bonnet , so 36k material is accepted for this usage.

 

[racookpe1978]

No. A flanged valve IS the single machined piece: body AND inlet flange AND outlet flange. How can you make a single piece out of two different materials? The bonnet is (almost always) made of the compatible material to body and its flanges.

 

[DANIAL AZIMI]

Si it shall be only 60k for whole part or 36k material could be used ??

 

[yudhichen]

API 6A gives user freedom to select what material designation (i.e. 36K to 75K) provided it complies with Table 5 of API 6A.
The concern is to see in holistic approach before we choose what material designation to use.

Let's say the valve body can be configured by using two material designation, i.e. 36K for flanges and 60K for valve body.
Based on load consideration, I don't think its a good idea to mix lower and higher strength.
Given it happens that way, 36K material shall be the weakest area when the whole area was subjected to uniform load during operational service.

 

[DANIAL AZIMI]

No i do not want to manufacture valve with two different material. I want to manufacture flanged valve with 45k material compeletly. It can be??

 

[yudhichen]

I'm not sure that's a good idea to use 45K material for valve flanged.
Table 5 of API 6A 20th Ed inherently suggest us to use 60K minimum for valve flanged,
since it consists of "body" and "flanged - integral end connection"